Camptothecin (CPT) is an alkaloid contained in the leaf or bark of Camptotheca acumination originated from China. CPT is a substance having excellent antitumor property; however, hardly soluble in water. Therefore, a semi-synthetic derivative of CPT, namely, irinotecan hydrochloride (7-ethyl-10-[4-(l-piperidino)-1-piperidino]carbonyloxycam ptothecin hydrochloride (hereinafter sometimes referred to as “CPT-11”) has been developed as a medicament (Japanese Patent Publication No. 3-4077). Irinotecan hydrochloride retaining high antitumor properties of CPT and mitigated in toxicity, has been widely used as an antitumor agent. When metabolized within the body, irinotecan hydrochloride is said to convert into 7-ethyl-10-hydroxycamptothecin (SN-38) (Japanese Patent Publication No. 62-47193), thereby giving rise to antitumor activity.
Irinotecan hydrochloride is administered to a patient primarily by intravenous injection. At present, therefore, irinotecan hydrochloride is sold and used in the form of an isotonic preparation treated with sorbitol or saline. Up to now, various attempts have been made to produce a preparation. For example, JP-A-1995-277981 reports a sustained release preparation, which is formed by adding a camptothecin derivative in a copolymer of collagen and 2-hydroxyethyl methacrylate. JP-A-1998-17472 reports a sustained release preparation formed by adding camptothecin or its derivative to a carrier formed of a polylactic acid-glycolic acid copolymer.